Devices for the generation of ultrasonics and their application to the preparation of emulsions

ABSTRACT

A device for generating ultrasonic waves in a fluid preferably used in emulsifying water and fuel oil and the like constructed of two side plates (each having at least one recess, occurring in adjacent pairs) and a thin steel membrane disk having a liquid access groove (discontinuities) cut out of said disk and extending into said recess such that the remaining portion of the membrane disk extending across each recess pair vibrates (preferably resonates) in the liquid flowing through said groove and into one of said recesses to pass out a discharge conduit extending from the base of such recess.

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DEVICES FOR THE GENERATION OF ULTRASONICS AND THEIR APPLICATION TO THEPREPARATION OF EMULSIONS Inventors: Louis Duthion, Paris; Claude CharlesDoyotte, Le Plessis Robinson; Claude Jean-Marie Seguela, Argenteuil;Gabriel Barthelemy, Paris; Alain Cinquanta; Yves Drapeau, both of LeHavre, all of France Assignee: Compagne Francaise De Raffinage,

Paris, France Filed: Sept. 5, 1972 Appl. No.: 286,061

Foreign Application Priority Data Sept. 3, 1971 France 71.31975 Dec. 20,1971 France 71.45738 7 June 27, 1972 France 72.23201 US. Cl 259/4,259/DIG. 30, 259/DIG. 43,

259/1310. 44 rm. Cl. 1301f 3/08, BOlf 5/06 Field of Search 259/4, 18,36, 60, 95,

259/DIG. 30, DIG. 43, DIG. 4 4; 261/D1G. 48

- [56] References Cited UNITED STATES PATENTS 3,744,762 7/1973 Schlicht259/4 3,658,302 4/1972 Duthion et a1 259/4 X Primary Examiner-Harvey C.Hornsby Assistant Examiner-Alan l. Cantor Attorney, Agent, orFirm-Curtis, Morris & Safford [57] ABSTRACT A device for generatingultrasonic waves in a fluid .preferably used in emulsifying water andfuel oil and 24 Claims, 13 Drawing Figures PATENTEDMAY 7 I974 SHEET 1 OF5 FIG.6

DEVICES FOR THE GENERATION OF ULTRASONHCS AND THEIR APPLICATION TO THEPREPARATION OF EMULSIONS The present invention relates to the generationof ultrasonics. More particularly it concerns devices for generatingultrasonic waves in a liquid medium, and the applications of thesedevices to the manufacture of emulsions; particularly emulsions of waterin fuel oil and emulsions of paraffin wax or microcrystalline wax inwater.

It is known that a jet of fluid emitted through the slit of a nozzle andhaving a thin blade located in front thereof with one end fixed, causessaid blade to vibrate. The vibration of the blade is accompanied by theprop agation in the fluid of waves whose frequency depends on thegeometry of the blade, its position, or more generally its situation,and the conditions of flow of the fluid.

Such a method can be carried out for a long period of time only by meansof devices which incorporate a vibrating blade of very great endurance(i.e., capable of vibrating without difficulty over a very extendedperiod of time). This requirement makes it necessary to use metals whichare particularly resistant to the fatigue caused by numerous periodicdeformations.

An object of the present invention is to perfect devices for generatingultrasonic waves in a fluid which does not require the use in themanufacture of the vibrating element of amaterial of particularly highperformance.

According to the present invention, this result is obtained by a specialarrangement of the vibrating element.

Embodying the present invention are devices for generating ultrasonicsin a fluid, which devices each comprise a membrane placed between twoside plates. Each plate has at least one recess. The membrane has afirst discontinuity which forms a passage through which the fluidpenetrates into the device between the two side plates. The firstdiscontinuity is continued by one or more second discontinuities whichform communica tion between the recesses (located in pairs on oppositesides of the membrane) with a conduit associated with each pair throughwhich the fluid is evacuated from the device.

In a first type of device, each side plate has only a single recess. Inthis type of device are associated on the one hand, with devices whosefirst discontinuity is located on the periphery of the membrane andwhose second discontinuity is the extension of the first discontinuity,and on the other hand, devices whose first discontinuity is located onthe periphery of the membrane and whose second discontinuity has a shapesuch that it defines a blade in the membrane. I

In a second type of device, each side plate is provided with a pluralityof recesses. The recesses of the two side plates are located oppositeeach other forming pairs. In this type of device, the firstdiscontinuity in the membrane is single and central. On the other hand,there are as many second discontinuities as there are pairs of recesses.The second discontinuities may be simple grooves forming a passagebetween the two recesses of a pair, or the second discontinuities may bemore complicated and have a plurality of branches which define blades inthe membrane.

In utilizing the foregoing devices for obtaining emulsions of water infuel oil for feeding boilers, the parameters (number of recesses, volumeof recesses, dimensions of the discontinuities of the membrane, etc.)are imparted values adapted to the power requirements of theinstallation. These parameters therefore have a specific value for eachgiven installation. However, the in vention also contemplates formingthe structure of said devices in such a manner that the same side platesare suitable for a wide range of given installations with only themembranes being specific to each given installation by separatelydetermining on the one hand the entire parameters specific to the sideplates and on the other hand the entire parameters specific tothemembrane. Thus the invention makes it possible to use standardelements which can be adapted to all installations whose thermal poweris, for instance, between 30 and 700 therms/hour. The advantageresulting herefrom is obvious to the man skilled in the art andtherefore need not be described.

Thus a further embodiment of the.present invention comprises:

a. Two side plates provided with at least two recesses each, therecesses of each side plate being located opposite those of the oppositeside plate;

b. A membrane placed between the two side plates,

each membrane having at least one first discontinuity which forms apassage through which the fluid penetrates into the device and which iscontinued by a second discontinuity which forms a communication in eachpair of recesses;

c. A conduit for the introduction of the fluid in communication with theoutside;

d. Conduits .through which the fluid is evacuated from each pair ofrecesses, the said conduits being in communication with the outside.

More generally in'this embodiment, the invention has standard sideplates with a maximum number of recesses, so that these side plates canbe used for a very wide range of rates of flow of fluid.

The adaptation to a given rate of flow is obtained by the selection ofan appropriate membrane which is placed between the standardized sideplates which makes it possible to vary three parameters, namely:

1. The number of pairs of recesses used;

'2. The thickness of the membrane;

3. The width of the discontinuities.

' The member of pairs of recesses used depends solely on the number ofdiscontinuities which the membrane has. The more discontinuities themembrane has the higher the number of pairs of recesses which it placesin communication, and the higher the rate of flow of fluid which theinstallation can accommodate all other things being equal) The thicknessof the membrane, which may vary, for

instance, between 10/100 and 20/100 of a mm by from 30 to 700therms/hour, may be encompassed by the use of the same pair'of sideplates having the number of pairs of recesses necessary for the feedingof a boiler of 700 therms/hour, with the particular power of theinstallation being satisfied by the use of a membrane which is placedbetween the two side plates and the thickness and number ofdiscontinuities of which are adapted to the power contemplated.

The invention also concerns in particular the application of the saiddevices to the obtaining of emulsions of paraffin or microcrystallinewax in water. By"paraffin wax is meant herein a particular parafiin waxor a mixtureof paraffin waxes having a crystalline structure and themelting point of which is between 45 C and 66 C. A large part of theparaffin wax (generally at least 40 percent by weight) is formed oflinear saturated aliphatic hydrocarbons. The oil content is less thanpercent by weight, and preferably less than 1 percent. Bymicrocrystalline wax is meant a mixture of saturated hydrocarbons ofmolecular weights higher than the paraffin wax. A microcrystalline waxhas more cyclic or branched saturated molecules and is generally richerin oil than a paraffin wax. As its name states, it is microcrystalline,and its melting point is between 66 C and 90 C. I

Emulsions of paraffin or microcrystalline wax have numerousapplications. They are used in particular to fireproof boards formed ofparticles of wood or other materials and for the sizing of paper.

In the prior art these emulsions are generally obtained by dispersingliquid paraffin wax by agitation in water in the presence of a certainamount of emulsifier in the medium. The agitation is generally effectedby means of an ordinary bladed agitator or by means of a turbine. Whenthe emulsifier is of an ionic nature, it may be synthesized in situ.Thus, for instance, anionic emulsions of paraffin wax are obtained byreaction of an amine with a fatty acid, the amine and the fatty acidbeing added either together or separately to the water and/or to theparaffin wax.

In the use of the devices in accordance with the present invention toprepare emulsions of paraffin or microcrystalline wax in water, thewater, the paraffin or.

microcrystalline wax, and the emulsifier agent are introduced through acommon inlet orifice into the 'emul-I sifying device, and the emulsionis'collected at an outlet orifice connected to at least'one pair ofrecesses located in the side plates. The difference in pressure presentbetween the inlet orifice and the outlet orifice is preferably greaterthan or equal to two bars.

In this specification and the accompanying drawings we have shown anddescribed a preferred embodiment of our invention and have suggestedvarious altematives and modifications thereof; but it is to beunderstood that these are not intended to be exhaustive and that manyother changes and modifications can be made within the scope of theinvention. These suggestions herein are selected and included forpurposes of illustration in order that others skilled in the art willmore fully understand the invention and the principles thereof and willthus be enabled to modify it and .embody it in a variety of forms, eachas may be best suited to the conditions of a particular use.

In the accompanying figures, devices or parts thereof embodying thepresent invention for the obtaining of emulsions of water in fuel oiland of emulsions of paraffin orv microcrystalline wax in water will bedescribed.

FIG. 1 shows in a frontal view, a membrane for use in a'device of thefirst type;

FIG. 2 shows, in cross section, along the line 22 of FIG. 3, a device inaccordance with a preferred embodiment of the present invention providedwith the membrane shown in FIG. 1;

FIG. 3 shows a section through the device along the line 3-3 of FIG. 2;

FIG. 4 shows, in front view, a modified membrane for use in a device ofthe first type;

FIG. 5 shows, in section, along the plane of symmetry of the membraneperpendicular thereto, a device provided with the membrane shown in FIG.4;

FIG. 6 shows, in a frontal view, a membrane for use in a device of thesecond type;

FIg. 7 shows, in section, along the plane of symmetry of the membraneperpendicular thereto, a device provided with the membrane shown in FIG.6;

FIGS; 8, 9, 10 and 11 concern a device in accordance with the inventionapplied to the obtaining of emulsions of water in fuel oil;

FIG. 8 shows in plan view the face of a first side plate having eightrecesses;

FIG. 9 shows in plan view the face of a second side .plate also havingeight recesses;

FIG. 10 shows in plan view a membrane provided with two notches;

FIG. 11 shows in section a device in accordance with the invention;

FIGS. 12 and 13 concern a device in accordance with the inventionapplied to the obtaining of emulsions of paraffin or microcrystallinewax in water;

FIG. 12 is an exploded view in perspective of an emulsifier, the twoside plates and the membrane being shown fanned apart for greaterclarity in the drawing:

FIG. '13 is a diagram of the arrangement of the emulsifier and of itsfeed members in a particular mounting.

Referring to FIGS. 1, 2 and 3, a circular thin membrane of stainlesssteel 1 comprises a discontinuity 2 in the form of a groove shown in theupper part of FIG. 1, having a radius of the membrane as its axis ofsymmetry. The discontinuity 2 is continued by a discontinuity 3. Thediscontinuities 2 and 3 form a groove. It is advantageous to provide thebottom of the groove with a bevel 4 on one face or both faces of themembrane.

The membrane 1 is placed between two side plates 5 and 6, respectivelyprovided with a cavity 7 and a cavity 8. The free space between the twoside plates, determined by the discontinuity 2, constitutes a passagewhose rectangular cross-section decreases towards the center of themembrane. The fluid penetrates into the device via this passage. Thediscontinuity 3 constitutes a passage for the fluid from one cavity intothe other.

. may comprise, for instance, clamping bolts which pass through thesolid parts of the side plates Sand 6 and of the membrane 1. It is alsopossible to screw one side plate onto the other.

The cavities 7 and 8 advantageously have their large axis parallel tothe axis of flow of the fluid in the discontinuity 2. They may be ofequal volume and of parallelepiped shape.

The fluid is introduced into the device by the discontinuity 2. Itescapes therefrom via the conduit 9.

The applicant believes that the generation of the ultrasonics can beexplained as follows:

The device operates as a fluid reciprocater (i.e., seesaw balance) dueto the existence of two cavities 7 and 8 fed by a single fluid inlet.The difference in pressure present between the cavities 7 and 8 causesthe membrane to vibrate. The optimum operating conditions are those forwhich the frequency of the swinging movement of the fluid from onecavity into the other is equal to the inherent frequency of themembrane 1. The dimensions of the cavities must be such that thephenomenon of resonance is obtained.

With reference to FIGS. 4 and 5, a circular thin membrane of stainlesssteel 10 has in its upper portion a discontinuity 12 shaped as a groove,having a radius of the membrane as its axis of symmetry. Thediscontinuity 12 is continued by a discontinuity 13 which has twobranches. The latter define a blade 14 which may advantageouslyterminate in a bevel 140 on one or both of its faces.

The membrane 10 is clamped between two side plates 15 and 16. The sideplates are provided with cavities 17 and 18, one of which has adischarge conduit 19.

Referring to FIGS. 6 and 7, a circular thin membrane of stainless steel20 has at its center a first discontinuity 21 which is followed by twosecond discontinuities 22 and 23. The latter each have two branches,each of which defines a blade, 24 and 25 respectively.

The fluid is introduced through a conduit 26. The side plates 27 and 28have two pairs of recesses 29 and 30 on the one hand and 31, 32 on theother hand. Each pair has a fluid evacuation conduit, 33 and 34respectively.

One application of the devices in accordance with the invention residesin their use for the production of emulsions and more particularlyemulsions of water in fuel oil. It is known that these emulsions can beburned instead of pure fuel oil. Their use decreases the proportion ofunburned hydrocarbons and carbon monoxide in the smoke.

A mixture of water and fuel oil in suitable proportions is introducedinto the internal recesses in the side plates via the discontinuity .2(or 12 or 21). The water and the fuel oil are mixed before introductionin a simple mixing chamber. It is also possible to have the water andthe fuel oil arrive through tw arms of a T or to have a water inletdebouch into a pipe through which the fuel oil flows. It is advisable inthis case to provide a nonreturn device in order to avoid the entranceof the fuel oil into the water conduit when the water pressureaccidentally drops. The groove 2, or 12, advantageously is providedupstream with-a readily accessible filtering device. This device, whichmay be reduced to a simple disk of fritted material, avoids the rapidclogging of the internal recesses of the emulsifier due to dustand theimpurities present in the fuel oil and in the water. i

The discontinuity 3 (or 13, or the discontinuities 22 and 23) providescommunication between the recesses of a pair with each other.

The emulsion is extracted via the conduits 9 (or 19,

or 33 and 34). The rate of flow of emulsion depends on the thickness ofthe blade and the width' of the discontinuity 2 or 12 or 21).

The frequency of the vibrations depends on the geometry of the inside ofthe device. This frequency may vary between 8,000 and 40,000 cycles persecond.

The first type of device is suitable for the feeding of small burners(20 to 40 therms/hour) as well as larger burners (up to 750therms/hour). The second type of device is suitable in particular forthe feeding of large burners (350 to 900 therms/hour).

EXAMPLE I This example relates FIGS. 1, 2, and 3. The characteristics ofthe membrane are as follows:

Diameter: 18 mm Thickness: 0.12 mm Nature: 18/8 steel Length of thediscontinuities 2 3) 3.6mm

Width of the discontinuity 2 at the periphery of the membrane: 3.4mm

Width of the discontinuity 3 measured on the bevel: 0.7 mm.

The membrane is clamped between two side plates of brass screwed to eachother at their periphery. The characteristics of the cavities are asfollows:

Depth: 1 mm Cross-sectional area: 11 mm X 5 mm The'feading of such adevice by 5.7 liters/hour of a mixture of domestic fuel oil and watercontaining 20% by volume water) produces an emulsion which can feed aburner of 30 thenns/hour. The frequency of the vibrations is 15,000cycles per second.

EXAMPLE II This example relates to a device in accordance with FIGS. 4and 5.

The characteristics of the membrane are as follows:

to a device in accordance with Diameter: 20 mm Thickness: 0.25 mmNature: steel Z 30 C 13 Length of the discontinuity l2): 4 mm Height ofthe blade (14): 16 mm Area of the blade (14): 3 mm X 6 mm Area of thediscontinuity 13): 1 mm X 6 mm The membrane is clamped between two sideplates. The characteristics of the recesses in the side plates are asfollows:

Depth: 1 mm Cross-sectional area: 1 mm X 6 mm Thefeeding of such adevice with 57 liters/hour of a mixture of domestic fuel oil and water20 percent water by volume) produces an emulsion which can feed a burnerof 300 therms/hour; the frequency of the vibrations is 1,250 cycles persecond.

EXAMPLE III FIGS. 6 and 7.

Diameter: 40 mm Thickness: 0.20 mm Nature: steel 18/8 Area of thediscontinuity (21): mm X 3 mm Area of the blades (24) and (25): 3 mm X 6mm The membrane is clampled between two side plates the recesses ofwhich have the following characteristics:

Depth: 1 mm Cross-sectional area: 11 mm X 6 mm mixture of light fuel oiland water percent water by side plate is beveled (dashed line'56) on theface opposite the face shown in FIG. 8. I Referring to FIG. 9:

The side plate 57 also has eight recesses 58 placed in the same positionas the recesses 52 of the side plate 51. Two protruding centering pins59 and 60 are machined to be able to penetrate into the blind holes 54and 55 respectively.

The side plates 51 and 57 constitute a pair of side plates which can beused over a wide range of fluid flow rates. The membrane which is placedbetween the pair of side plates determines the exact application of thedevice within said range, which is related on the one hand to thethickness of the membrane and on the otherhand to the width and numberof notches which the latter has. This number may in the present case bebetween one and eight.

Referring to FIG. 10: I I

The membrane 61, whose diameter isequal to the diameter of the sideplates 51 and 57, has two notches 62 and 63. These notches are composedof a first discontinuity64 of the membrane formed at the periphery ofthe membrane and a second discontinuity 65 which is the extension of thefirst discontinuity. The edges of the second discontinuity are parallelto each other. The first and seconddiscontinuities form a groove or asingle passage. The bottom of the groove which is perpendicular to theedges of the second discontinuity can be provided with a bevel. Thebevel has not been shown.

in FIG. 10. The'notches 62 and 63 have the same axes of symmetry as therecesses of the side plates 51 and 57. It is not necessary for the twonotches to be located alongside of each other.

The membrane 61 has two holes 66 and 67 of the same size, located in thesame positions as the holes 54 and 55 respectively;

Referring to FIG. 11:

The part 68 has a bore hole 69 in which the side plates 51 and 57 areplaced. The membrane 61 is placed between the side plates. The bore hole69 is continued by an internally threaded part 70 in which plate 51. Theperiphery of the concealed face of the there is screwed the threadedportion 71 of a part 72. By tightening the parts 68 and 72 together,they press the side plates 51 and 57 very hard against each other. Thereference number 73 designates a ring. The fluid or mixture of fluids isintroduced through the orifice 74 which debouches into the bore hole 69of the part 68 at the level of the volume 75 which acts as distributionconduit. The fluid or the emulsion is extracted from the pairs ofrecesses by the conduits 53 and then from the device by the conduit 76which terminates in a threaded portion 77.

The loss of head can be maintained substantially constant whatever therate of flow by varying the characteristics of the membranes (thickness.number and width of the discontinuities).

Thus in the case of the feeding of a boiler, the drop in pressure in thefluids taking place between the inlet and outlet of the device issubstantially constant and independent of the power of the boiler. Thisdrop in pressure may, for instance, be between 2 and 4 bars.

The frequency of vibration may be between 10,000 and 25,000 cycles persecond.

' The use of a filtering device is necessary if it is desired that theemulsifying device retain its entire effectiveness for a long period oftime.

Example IV below, which is given by way of further illustration, relatesto a device in accordance with FIGS. 8, 9, 10 and 11.

EXAMPLE IV The characteristics of the side plates are as follows:

Diameter: 40.0 mm

Width of the recesses: 5.0 mm

Total length of the recesses: 10.5 mm

Distance from the bottom of a recess to the center of the side plate:7.0 mm

Distance from the center of the conduits 53 to the center of the sideplate: 15 mm Diameter of the conduits 53: 3 mm Diameter of the blindhole 54 and of the pin 59: 3

Diameter of the blind hole 55 and of the pin 60: 3

The characteristics of the membrane are as follows:

Referring to FIGS. 12 and 13, there will now be described an applicationof the invention for obtaining emulsions of paraffin or microcrystallinewax in water:

Referring to FIG. 12, the membrane 101 having a discontinuity 102 and abevel 103 is placed between two I side plates 104 and 105 (when theapparatus is in operating position), each provided with a recess 106 and107. The mixture of paraffin wax, water and emulsifying agent isintroduced into the emulsifier through the discontinuity 102..The jet ofemulsion is recovered via the conduit 108 which communicates with theinside of inlets converge into a single conduit before introduc-.

tion into the emulsifier.

The components of the emulsion should be introduced under pressure intothe emulsifying device. For this purpose one can employ either thepressure of an inert gas acting on the surface of each of the componentsplaced in a feed tank, or a pump placed on the path of each of thecomponents between the feed tank and the place of convergence of thedifferent components.

The pressure of the jet of emulsion at the outlet of the .device can beregulated by the use of an outlet nozzle.

In the absence of a nozzle, the outlet pressure is equal to atmosphericpressure.

The applicants have noted that the difference which exists betweenthevalues of the pressure at the inlet and at the outlet of the deviceshould be equal to at least two bars. If the difference in pressure isless than two bars, the emulsion is very thick and it is not stable, asshown by the tests reported below.

The components of the emulsion must be introduced into the emulsifyingdevice at a temperature generally between 80 and 99 C. The exact valuedepends on the paraffin wax used. For a given paraffin wax, it is notgreater than the temperature to be employed in the conventional emulsionmanufacturing method.

A simplified flow sheet of the emulsifier and the feed members is givenin FIG. 13.

The emulsifier 111 is fed via the line 112 with a mixture of paraffinwax, emulsifying agent and water. The paraffin wax and the emulsifyingagent are conducted towards the emulsifying device 111 by 'the line 113under the effect of the pressure exerted by nitrogen located above thefree surface of the liquid in the tank 114. The water is conducted bythe line 115, under the effect of the nitrogen pressure in the tank 116,towards the emulsifying device 111. The reference numbers 117 and 118designate filters. The lines 113 and 115 are each provided with .a gatevalve 119 and 120 respectively) and with a check'valve (121 and 122respectively). The nitrogen is brought by the line 123 into the tanks114 and 116-. The nitrogen pressure is fixed at the desired value. Thetanks 114 and 116 are fed by the lines 124 and 125 respectively. Theemulsion is extracted from the emulsifying device 111 by the line 126which'may possibly have a nozzle 127.

The charging of the tanks 114 and 116 can be effected intermittently orcontinuously via the lines 124 and 125. The reference number 128designates a mechanism for the charging of the paraffin wax, thereferences 129 and 130 designating gate valves.

The collection of parts described above are located within an enclosure131 whose temperature is maintained at about 95 C. Outside of thisenclosure is the emulsion receiving tank 132.

In the diagram described 'above, agent is added to the paraflin waxbefore the, production of the emulsion. The latter can be effected, forinstance, with nonionic emulsifying agents of the type of alkyl phenolor fatty alcohol condensate and ethylene or propylene oxide, or estersof fatty acids and polyalcohols, or else amides derived from aminatedfatty acid and alkylol. The emulsifying agents of the same type may beadded to the water prior to the preparation of the emulsion rather thanto the parafiin wax.

When the emulsifying agents are synthesized in situ, which is, forinstance true of the anionic emulsifiers of the amine soap type, thecomponents of the emulsifying agent may be added either together withthe water or the paraffin wax, or with the water in the case of one ofthem and the paraffin wax in the case of the other.

The invention is further illustrated by Example V below.

EXAMPLE v By means of an emulsifying device identical to that shown inFIG. 12, the characteristics of which are:

diameter of the membrane 18 mm thickness of the membrane ll/l00 mm widthof the discontinuity /100 mm depth of the discontinuity 3.5 mm

Test number 1 2 3 4 Composition of the emulsion (by wt.):

Emulsifying agent (1)-. Paratfin wax (2) Water AP (in bars) Propfrtiesof the emulsion:

iscosity at 20 C. (in Engler) Thick Conductuponsheking Centrlfuging(5)Diameter of the par ticles (in 14)- Stable 0 Al fla r-ghee between thepressures prevailing at the inlet and outlet of the emulsifying device.7 I

1. Composition of the emulsifyingagent:

mixture of sorbitan monostearate and stearic ether of polyethyleneoxide.

2. Physical characteristics of the paraffin wax:

melting point: 52 C viscosity at C: 3.2 cst oil content: 2 percent byweight 3. Test No. 1 was carried out in the absence of vibratingmembrane.

4. Measured with i 10 blows/minute, amplitude equal to 8 i 1 cm for 60minutes. Stable means that no rupture or thickening occurs.

5. Measured in percent by volume) of water separating out under anacceleration 240 times the accelerationof gravity maintained for 30minutes.

6. The emulsion T was preparedby the conventional method, that is to sayby agitation of a mixture of paraffin wax, water an d emulsifying agentthe emulsifying rpm. The tests reported in the preceding table show that.emulsions of good quality are obtained when the difference in pressureis equal to or greater than two bars. They are less viscous than theemulsion T prepared by conventional means.

We claim:

1. Device for generating ultrasonics in a fluid, comprising a membrane,two side plates located on each side of the membrane and each having atleast one recess, said recesses forming adjacent opposing pairs, saidmembrane having at least a first discontinuity which forms a passagethrough which the fluid penetrates into the device and at least a seconddiscontinuity extending the'first discontinuity and forming acommunication between each pair of said recesses located on each side ofthemembrane, each such second discontinuity leaving a substantialportion of said membrane extending between each respective pair ofrecesses sufficient to effectively vibrate, and a conduit from onerecess of each pair via which the fluid is evacuated from the device.

2. Device according to claim 1, each side plate having a single recess.3. Device according to claim 1, said first discontinuity being locatedon the periphery of the said membrane; said second discontinuity beingan extension of the said first discontinuity, and the'first and seconddiscontinuities consisting of a single groove.

4. Device according to claim 3, wherein said membrane has at least oneaxis of symmetry, said recesses form pairs which have equal volumes andare symmetrical with respect to a plane perpendicular to said membraneat its axis of symmetry.

5. Device according to claim 1, said first discontinuity being locatedat the 'periphery of the said membrane and said second discontinuityhaving two branches defining a blade in the membrane.

6. Device according to claim 5, wherein said membrane has at least oneaxis of symmetry, said recesses form pairs which have equal volumes andare symmetrical with respect to a plane perpendicular to said membraneat its axis of symmetry.

7. Device according to claim 1, each side plate having at least tworecesses.

8. Device according to claim 7, further comprising a plurality of seconddiscontinuities, said first'dis'continuity being located substantiallyat the center of said membrane and said second discontinuitiesconstituting grooves.

9. Device according to claim 8, wherein said membrane has at least oneaxis of symmetry, said recesses- ,form pairswhich have equal volumes andare symmet: rical with respect to a plane perpendicular to said membraneat its axis of symmetry.

10. Device according to claim 7, the number of first discontinuities ofthe membrane being between one and the number of recesses of each sideplate.

11. Device according to claim 10, said first discontinuity ordiscontinuities being located on the periphery -for preventing therotation of the said membrane between said side plates.' I

15. Device according to claim 14, said means being formed of lockingpins rigidly connected with one of the side plates which pass throughholes provided in the membrane and engage in blind holes provided in theother side plate.

16. Device according to claim 10, comprising means which press the sideplates strongly against each other.

17. Device according to claim 7, said first discontinuity being locatedsubstantially atthe center of the said membrane and further comprising aplurality of second discontinuities, each having several branchesdefining blades in the membrane.

18. Device according to claim 17, wherein said membrane has at least oneaxis of symmetry, said recesses form pairs which have equal volumes andare symmetrical with respect to a plane perpendicular to said membraneatits axis of symmetry.

19. Device according to claim 1, wherein said membrane has at least oneaxis of symmetry, said recesses form pairs which have equal volumes, andare symmetrical with respect to a plane perpendicular to said membraneat its axis of symmetry.

20. Device according to claim 1 for the obtaining of emulsions of waterin fuel oil, comprising filtering means for cleaning said fuel oil andsaid water, means for mixing the water, fuel oil, and any otheringredients in desired proportions, and means for feeding saidingredients into the passage formed by the said first discontinuity andfor maintaining a pressure drop of at least 2 bars.

21. Device according to claim 1 for the obtaining of emulsions ofparaffin or microcrystalline wax in water further comprising means forsupplying a mixture of water, paraffin or microcrystalline wax, and anemulsifying agent together under a pressure at least more than two barsgreater than the pressure in the said evacuation conduit.

22. Device according to claim 21, further comprising means for havingthetemperature of said mixture at the inlet being between and 99 C.

23. Device according to claim 21, said evacuation conduit comprising anozzle.

24. Device according to claim 21, further comprising means formaintaining the absolute pressure of said mixture at the inlet at morethan 3 bars.

1. Device for generating ultrasonics in a fluid, comprising a membrane,two side plates located on each side of the membrane and each having atleast one recess, said recesses forming adjacent opposing pairs, saidmembrane having at least a first discontinuity which forms a passagethrough which the fluid penetrates into the device and at least a seconddiscontinuity extending the first discontinuity and forming acommunication between each pair of said recesses located on each side ofthe membrane, each such second discontinuity leaving a substantialportion of said membrane extending between each respective pair ofrecesses sufficient to effectively vibrate, and a conduit from onerecess of each pair via which the fluid is evacuated from the device. 2.Device according to claim 1, each side plate having a single recess. 3.Device according to claim 1, said first discontinuity being located onthe periphery of the said membrane, said second discontinuity being anextension of the said first discontinuity, and the first and seconddiscontinuities consisting of a single groove.
 4. Device according toclaim 3, wherein said membrane has at least one axis of symmetry, saidrecesses form pairs which have equal volumes and are symmetrical withrespect to a plane perpendicular to said membrane at its axis ofsymmetry.
 5. Device according to claim 1, said first discontinuity beinglocated at the periphery of the said membrane and said seconddiscontinuity having two branches defining a blade in the membrane. 6.Device according to claim 5, wherein said membrane has at least one axisof symmetry, said recesses form pairs which have equal volumes and aresymmetrical with respect to a plane perpendicular to said membrane atits axis of symmetry.
 7. Device according to claim 1, each side platehaving at least two recesses.
 8. Device according to claim 7, furthercomprising a plurality of second discontinuities, said firstdiscontinuity being located substantially at the center of said membraneand said second discontinuities constituting grooves.
 9. Deviceaccording to claim 8, wherein said membrane has at least one axis ofsymmetry, said recesses form pairs which have equal volumes and aresymmetrical with respect to a plane perpendicular to said membrane atits axis of symmetry.
 10. Device according to claim 7, the number offirst discontinuities of the membrane being between one and the numberof recesses of each side plate.
 11. Device according to claim 10, saidfirst discontinuity or discontinuities being located on the peripheRy ofthe said membrane, and the said second discontinuity or discontinuitiesbeing in the extension of the first, each pair of first and seconddiscontinuities constituting a single groove.
 12. Device according toclaim 11, further comprising a distributing conduit which receives saidfluid and distributes it to the periphery of said membrane in flowcommunication with said first discontinuity.
 13. Device according toclaim 12, comprising means for preventing the rotation of the saidmembrane between said side plates.
 14. Device according to claim 10,comprising means for preventing the rotation of the said membranebetween said side plates.
 15. Device according to claim 14, said meansbeing formed of locking pins rigidly connected with one of the sideplates which pass through holes provided in the membrane and engage inblind holes provided in the other side plate.
 16. Device according toclaim 10, comprising means which press the side plates strongly againsteach other.
 17. Device according to claim 7, said first discontinuitybeing located substantially at the center of the said membrane andfurther comprising a plurality of second discontinuities, each havingseveral branches defining blades in the membrane.
 18. Device accordingto claim 17, wherein said membrane has at least one axis of symmetry,said recesses form pairs which have equal volumes and are symmetricalwith respect to a plane perpendicular to said membrane at its axis ofsymmetry.
 19. Device according to claim 1, wherein said membrane has atleast one axis of symmetry, said recesses form pairs which have equalvolumes and are symmetrical with respect to a plane perpendicular tosaid membrane at its axis of symmetry.
 20. Device according to claim 1for the obtaining of emulsions of water in fuel oil, comprisingfiltering means for cleaning said fuel oil and said water, means formixing the water, fuel oil, and any other ingredients in desiredproportions, and means for feeding said ingredients into the passageformed by the said first discontinuity and for maintaining a pressuredrop of at least 2 bars.
 21. Device according to claim 1 for theobtaining of emulsions of paraffin or microcrystalline wax in waterfurther comprising means for supplying a mixture of water, paraffin ormicrocrystalline wax, and an emulsifying agent together under a pressureat least more than two bars greater than the pressure in the saidevacuation conduit.
 22. Device according to claim 21, further comprisingmeans for having the temperature of said mixture at the inlet beingbetween 80* and 99* C.
 23. Device according to claim 21, said evacuationconduit comprising a nozzle.
 24. Device according to claim 21, furthercomprising means for maintaining the absolute pressure of said mixtureat the inlet at more than 3 bars.